Experimental And Theoretical Study On Fully Assembled Steel-Concrete Composite Beams And The Connectors

At present,China's construction waste accounts for about 40%of all waste,and the quantity is quite large.How to reduce the proportion of abandoned structural components has become a task of scientific research personnel in the field of structural engineering.Existing assembly-type composite beam implementation schemes are generally difficult to disassemble.It is difficult to partially replace and recycle difficult problems.If breakthroughs are made in local replacement and recycling,the proportion of recyclable composite beam components will be increased,and the consumption of energy,manpower,materials and other resources will be reduced to better achieve sustainable development.According to the problem that has not been completely solved in the field of composite beams,this paper develops a new type of fully assembled composite beam.The main components of this fully assembled composite beam include precast concrete slabs,steel beams and TJ fasteners with pre-embedded C-shaped steel channels.The new fully assembled steel-concrete composite beam is dry-connected,eliminating the need for cast-in-place concrete,speeding up construction,quick installation,easy disassembly and repair,and meeting recyclable requirements.In order to study the mechanical properties of the new fully assembled steel-concrete composite beam,the initial push-out test was conducted to study the effects of different steel channel forms,cyclic loading and the number of fasteners on shear performance.Through the test phenomenon,the failure mode and force mechanism of the new fully assembled steel-concrete composite beam are analyzed.The relationship between the torque applied by the fastener and the pre-tightening force is derived,and the simplified calculation formula of the shear capacity of the fastener is obtained.Based on the preliminary push-out test,we further proposed an improved new fully assembled steel-concrete composite beam form,eliminating the concrete between the steel beam and the steel channels,preventing local damage here.And the universal high-strength screw end is provided with a universal joint,so that the high-strength screw end of the fastener is more closely contacted with the inner side of the steel beam flange.Further research on the new fully assembled steel-concrete composite beam is carried out.Through the strain measurement of the fastener,the pre-tightening formula of the elastic-plastic phase of the fastener is proposed.Through the analysis of the load slip curve,The shear-slip constitutive relationship of two types of specimens is proposed.Based on the above experimental research,this paper designs the bending test of the new fully assembled composite beam,and carries out finite element modeling analysis.The model calculation results are in good agreement with the test,and are calculated by a large number of finite element models.Data analysis,the calculation formula of the deflection of the elastic stage and the practical calculation formula of the ultimate bearing capacity of the bending are proposed.